Irrespective of what's happening to suppliers on the Chinese side, the biggest impact will be from the ending of the last decade of remarkably porous customs enforcement of mail in the US. The system wasn't prepared for the number of packs from China doubling every two years to well over a billion annually now, thanks to the "de minimus" loophole.
99% of mailed parcels from China bypass customs inspection altogether because customs just doesn't have the capacity.
There was a reason you couldn't simply have cheap steroids shipped from China to your house 20 years ago, and it's going to return to that. The Chinese know this and have been quietly preparing alternate routes for a while. All these "US Warehouses" haven't been popping up because they're dedicated to good customer service.